Integrated circuit electrical protection device
View Patent ↗An integrated circuit electrical protection device is disclosed that includes a semiconductor substrate and a plurality of transistor fingers partitioned into a plurality of segments. The segments are distinguished from one another by well-ties spaced apart from each other within a source/drain region that is shared by adjacent segments.
1. An integrated circuit device comprising:
a Field Effect Transistor (FET) comprising a first transistor finger and a second transistor finger, wherein the first transistor finger and the second transistor finger share a first source/drain region of a first conductivity type residing in a well region having a second conductivity type, wherein the first conductivity type is opposite the second conductivity type; and
a first well-tie between a first portion of the first source/drain region and a second portion of the first source/drain region, the first well-tie coupled to a voltage reference terminal that provides a fixed bias voltage for the well region during normal operation of the integrated circuit.
2. The device of claim 1 , wherein the first well-tie is between the first and second portions of the first source/drain region in a lateral direction.
3. The device of claim 1 , wherein the first well-tie is between the first and second portions of the first source/drain region in a transverse direction.
4. The device of claim 1 , wherein the first well-tie is surrounded by the first source/drain region.
5. The device of claim 1 further comprising:
a second well-tie between the second portion of the first source/drain region and a third portion of the first source/drain region, wherein the first well-tie and a surrounding dielectric region are surrounded by the first source/drain region.
6. The device of claim 5 , wherein the second portion of the first source/drain region is at a center location of the first source/drain region in a transverse direction.
7. The device of claim 5 , wherein the first well-tie is at a center location of the first source/drain region in a transverse direction.
8. The device of claim 5 , wherein a gate of the first transistor finger and a gate of the second transistor finger are coupled together.
9. The device of claim 5 , wherein a ratio of a first dimension to a second dimension is at least 1:1, wherein the first dimension is a shortest distance in a transverse direction between a dielectric of the first well-tie and a dielectric of the second well-tie, and the second dimension is a length of the first well-tie and its surrounding dielectric in the transverse direction.
10. The device of claim 1 , wherein a gate of the first transistor finger and a gate of the second transistor are coupled together.
11. The device of claim 1 , wherein the first source/drain region is a source region that is coupled to a second voltage reference terminal.
12. A method comprising:
providing a first current from a source/drain region of a first Field Effect Transistor (a first FET) to a first well region of the first FET in response to an overstress event;
receiving a snapback portion of the first current at a second source/drain region of the first FET; and
receiving, via a current path, a biasing portion of the first current at a second well region closer to a second FET than to the first FET, wherein the current path includes a third well region abutting a shared source/drain region that is shared by the first FET and the second FET, and that extends continuously from a gate of the first FET to a gate of the second FET.
13. A device comprising:
an integrated circuit electrical protection device comprising
a Field Effect Transistor (FET) comprising a plurality of transistor fingers, including a first transistor finger and a second transistor finger, each of the plurality of transistor fingers comprising a gate portion, a source region, and a drain region shared with another one of the plurality of transistor fingers, wherein the first transistor finger shares a first drain region with the second transistor finger, and the source region is coupled to a fixed voltage reference terminal, and
a first well-tie between a first portion of the first drain region and a second portion of the first drain region, the first well-tie coupled to the fixed voltage reference terminal that is to provide a fixed voltage during normal operation.
14. The device of claim 13 wherein the first well-tie is surrounded by the first drain region.
15. The device of claim 13 further comprising:
a second well-tie is between the second portion of the first drain region and a third portion of the first drain region.
16. The device of claim 15 , wherein the second portion of the first drain region is at a center location of the first drain region relative a width of the first drain region.
17. The device of claim 15 , wherein the first well-tie is at a center location of the first drain region in a transverse direction.
18. The device of claim 15 , wherein ratio of a dimension between a dielectric surrounding the first well-tie and a dielectric surrounding the second well-tie to a width of the first well-tie is at least 1:1, wherein the dimension and the width are relative to a width of the first drain region.
19. The device of claim 13 , wherein
the plurality of transistor fingers further include a third transistor finger and a fourth transistor finger, the third transistor finger shares a second drain region with the fourth transistor finger; and
the FET transistor further includes a second well-tie between a first portion of the second drain region and a second portion of the second drain region, the second well-tie coupled to the fixed voltage reference terminal, and the second and third transistor fingers are members of a set of the plurality of transistor fingers, wherein no well-ties reside between gates of the members of the set.
20. The device of claim 19 , wherein the first well-tie is one of a first plurality of well-ties within the first drain region, the second well-tie is one of a second plurality of well-ties within the second drain region.